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RE: D-AR0062.2: Authentication for data

From: David Booth <dbooth@w3.org>
Date: Sun, 05 May 2002 21:25:37 -0400
Message-Id: <5.1.0.14.0.20020505202018.02913e80@localhost>
To: "Joseph Hui" <jhui@digisle.net>, "ECKERT,ZULAH (HP-Cupertino,ex1)" <zulah_eckert@hp.com>, "Bick, Bob (LNG)" <robert.bick@lexisnexis.com>, "Hugo Haas" <hugo@w3.org>, <www-ws-arch@w3.org>
If I am understanding your explanation, it sounds like "data 
authentication" basically boils down to:

         "data authentication" = "data integrity" + sender authentication

Thanks for the explanation.

In any case, I think it would be helpful to re-word requirement D-AR0062.2, 
to explicitly separate out and identify the issues of "data integrity" and 
"sender authentication".

At 11:43 AM 5/3/2002 -0700, Joseph Hui wrote:
> > -----Original Message-----
> > From: ECKERT,ZULAH (HP-Cupertino,ex1) [mailto:zulah_eckert@hp.com]
> > Sent: Friday, May 03, 2002 11:02 AM
> > To: Joseph Hui; Bick, Bob (LNG); Hugo Haas; www-ws-arch@w3.org
> > Cc: ECKERT,ZULAH (HP-Cupertino,ex1)
> > Subject: RE: D-AR0062.2: Authentication for data
> >
> > Joe,
> >
> > Isn't this commonly refered to as Data Origin Authentication
> > (as opposed to "data authentication")?
>
>Not exactly, though in some loose context some writer treat the two 
>interchangeably.
>Here's the nuance.  Data Origin Authentication is more like confirming
>to Bob that the data came from Alice, but it doesn't tell whether the
>data has been altered (so Bob doesn't have to compute the checksum or
>message digest for verifying data integrity.)  Of course, in real life
>what good is to Bob to know the message came from Alice but not know
>if the message has been altered, if Bob and Alice are serious about
>security?  This leads to data authentication.
>Data authentication means confirming to Bob the data came from Alice and it
>has not been altered.  It encompasses Data origin authc and data integrity.
>E.g. Alice and Bob did a TLS handshake, through their sharing of
>a master secret, they share a set of keying material for deriving
>the symmetric keys known only between them.
>One of the symmetric keys is for computing the HMAC-SHA1, say H.
>Before sending a message M to Bob, Alice computes a message digest
>with HMAC-SHA1, which is a message digest algorithm incorporating H,
>resulting in D.  Alice sends M and D to Bob.  (Note that M can be in
>either plaintext or ciphertext, depending on if Alice and Bob see a
>need for Confidentiality.)  Bob now hashes M with H to get d.
>If d == D, then voila -- Bob knows M came from Alice unaltered.
>
>Joe Hui
>Exodus, a Cable & Wireless service
>=============================================
>
> >
> > Zulah
> > Hewlett-Packard Company
> >
> > -----Original Message-----
> > From: Joseph Hui [mailto:jhui@digisle.net]
> > Sent: Friday, May 03, 2002 9:07 AM
> > To: Bick, Bob (LNG); Hugo Haas; www-ws-arch@w3.org
> > Subject: RE: D-AR0062.2: Authentication for data
> >
> >
> > > -----Original Message-----
> > > From: Bick, Bob (LNG) [mailto:robert.bick@lexisnexis.com]
> > [snip]
> > > I'd suggest we use the standard terms "data integrity" and
> > > "non-repudiation"
> > > in that case rather than "data authentication". Perhaps this
> > > may be more
> > > clear.
> >
> > Data authentication IS a widely understood (or standard, if
> > you so chose) term.
> >
> > Do not confuse "data integrity" and "non-repudiation" with
> > data authentication.  They are not the same.
> >
> > Joe Hui
> > Exodus, a Cable & Wireless service
> > ==========================================
> > >
> > > Bob
> > >
> > > -----Original Message-----
> > > From: Joseph Hui [mailto:jhui@digisle.net]
> > > Sent: Thursday, May 02, 2002 9:12 PM
> > > To: Hugo Haas; www-ws-arch@w3.org
> > > Subject: RE: D-AR0062.2: Authentication for data
> > >
> > >
> > > Data authentication -- authenticate that the data came from
> > the right
> > > source.
> > > Getting acquainted with HMAC may help further.
> > >
> > > E.g. asking you to produce a driver's license authenticates you (by
> > > biometrics)
> > > to me that you're Hugo.  That's __peer (or party, or source)
> > > authentication__.
> > > Computing the hash of a message that incorporates a secret
> > > shared by you and
> > > me
> > > allows me to authenticate that the message has not been
> > altered and it
> > > came from you.  That's __data authentication__.  HMAC is one
> > > way of doing
> > > this.
> > > Digital Signature is another way; but it requires Public Key
> > > Encryption
> > > (PKE),
> > > thus a bit more expensive.
> > >
> > > Joe Hui
> > > Exodus, a Cable & Wireless service
> > > ==================================================
> > > > -----Original Message-----
> > > > From: Hugo Haas [mailto:hugo@w3.org]
> > > > Sent: Thursday, May 02, 2002 2:02 PM
> > > > To: www-ws-arch@w3.org
> > > > Subject: D-AR0062.2: Authentication for data
> > > >
> > > >
> > > > My apologies, I was talking about D-AR0062.2, not D-AR006.2.1.
> > > >
> > > > * Hugo Haas <hugo@w3.org> [2002-05-02 16:59-0400]
> > > > > D-AR0062.2 reads:
> > > > >
> > > > >           + D-AR0062.2 The security framework must include
> > > > Authentication
> > > > >             for data (sent and received by
> > communicating parties).
> > > > >
> > > > > D-AR0062.1 talks about parties authentication. D-AR0062.5
> > > > talks about
> > > > > data integrity. It is not clear to me what data
> > authentication is.
> > > >
> > > > --
> > > > Hugo Haas - W3C
> > > > mailto:hugo@w3.org - http://www.w3.org/People/Hugo/ -
> > > > tel:+1-617-452-2092
> > > >
> > > >
> > >
> >

-- 
David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Sunday, 5 May 2002 21:25:41 GMT

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